Apparatus for producing parallel light



Jan. 24, 1967 BRQWNING APPARATUS FOR PRODUCING PARALLEL LIGHT 3Sheets-Sheet 1 Original Filed March 4. 1963 l/ 2 E: 5; :::C

G mN mm m0 R B N E m 'llll' ATTORNEYS Jan. 24, 1967 1. BROWNING3,300,266

APPARATUS FOR PRODUCING PARALLEL LIGHT Original Filed March 4. 1963 I5Sheets-Sheet 2 SERVO a 44 VARIABLE VOLTA E SPEED MOTOR F AMPLIFI R 5 6 55 9 l POWER AMPLIFI EQUALIZ INVENTOR. IBEN BROWNING ATTORNEYS Jan. 24,1967 BROWNING 3,300,265

APPARATUS FOR PRODUCING PARALLEL LIGHT Original Filed March 4, 1963 3Sheets-Sheet 5 mvsm OR IBEN BROWNING BY ATTORNEYS United States Patent3,300,266 APPARATUS FOR PRODUCING PARALLEL LIGHT Iben Browning,Sunnyvale. Calif. (745 Distel Drive, Los Altos, Calif. 94022) Originalapplication War. 4. 1963, Ser. No. 262,562. Di-

vided and this application Mar. 24, 1966, Ser. No. 537,059

1 Claim. (Cl. 350-96) The present invention is directed in general toapparatus for producing parallel light and applicable for use. forexample, in photographing and reproducing large quantities ofinformation in an extremely compact manner.

This application is a divisional application of US. Serial No. 262,562for Photographic Recording and Reproduction Method and Apparatus. filedMarch 4, 1963.

The photographic recording and reproducing apparatus according to theabove-mentioned parent application utilizes a mosaic lens array having afront surface consisting of the front surfaces of the lenses, a filmplate positioned behind the back surface of the array and means formoving the film plate at a slight angle with respect to the alignedlenses, each of the individual lenses of the array receiving light on adistinct portion of the front surface of the array and focusing asubstantial portion of that light in a minute spot on the film platemoving relative thereto to cause the spots to trace streaks on the filmplate, the streaks being traced parallel to each other and each of thespots having an area only a small fraction of the area of the portion ofthe front surface from which it originated. The film plate is exposed byfocusing the image to be reproduced upon the lens mosaic and tracingstreaks on the film plate. Then the film plate is developed and run backthrough the device with parallel light directed onto the lens mosaic forfocusing through the developed film plate for reproduction of thepreviously recorded image.

The object of the present invention is the provision of a novel meansfor producing substantially parallel light including a wedge oftransparent material having broad faces slightly inclined with respectto one another and a pick up lens with a saw-toothed surface positionedagainst a flat surface of the wedge for picking up and transmittinglight passing out of the flat surface of the wedge.

Still another feature and advantage of this invention lies in the factthat substantially parallel light is produced from a miniature lamputilizing inexpensive transparent material.

Still another feature and advantage of this parallel light producingstructure lies in the fact that substantially all of the lightintroduced into the wedge is reflected until it emerges substantiallyparallel with other emerging light.

Other objects of the present invention will become ap-' parent uponreading the following specification and referring to the accompanyingdrawings in which similar characters of reference representcorresponding parts in each of the several views.

In the drawing:

FIG. 1 is a side elevational view, partially broken away, of a cameraincorporating features of the present invention;

FIG. 2 is an enlarged sectional view of that portion of the structureshown in FIG. 1 delineated by line 2-2:

FIG. 3 is a front view, partially broken away, of that portion of thestructure of FIG. 1, taken along line 3-3;

FIG. 4 is a plan view of a film plate produced by the camera in FIG. 1;

FIG. 5 is a plan view of an alternative lens mosaic construction;

3,300,266 Patented Jan. 24, 1967 FIG. 6 is a side sectional view of analternative lens mosaic construction:

FIG. 7 is a side elevational view. partially in section. of an apparatusfor viewing the film taken with the structure of FIG. 1:

FIG. 7a is a fragmentary view of the belt shown in FIG. 7.

FIG. 8 is a back view of that portion of the structure shown in FIG. 7taken along line 8-3:

FIG. 9 is a cross-sectional view of that portion of the structure shownin FIG. 8 taken along line 9--9 and including other structure in blockform:

FIG. 10 is an enlarged view of that portion of the structure shown inFIG. 7 delineated by line 10-10:

FIG. 11 is a plan view of a portion of a film plate illustrating onesound track embodiment of the present invention:

FIG. 12 is a side view. partially in section. of apparatus for producinga sound track with the film plate of FIG. 11'.

FIG. 12a is a side view of the apparatus of FIG. 12 taken along line12a-12a:

FIG. 13 is a plan view of a portion of a film plate illustrating analternative sound track:

FIG. 14 is a top view, partially in section. of apparatus for producinga sound track with the film plate shown in FIG. 13;

FIG. 14a is a side view of the apparatus of FIG. 12 taken along line13a13n;

FIG. 15 is a perspective view of one photographic reproduction apparatusutilizing the present invention;

FIG. 16 is a cross section view of the film plate shown in FIG. 15 takenalong line 16-16;

FIG. 17 is a rear view of the film plate shown in FIG. 16 taken alongline 17-17: and

FIGS. 18 and 19 are plan views of a portion of a film plate illustratingdifferent manners of utilizingthis invention.

While the invention is particularly adapted and will be first describedfor the production of a photographic record of a continuous event andthe visual display of such a record, the invention is also useful foruse in providing a record of a sequence of separate frames and thesequential display of such frames as will later be described in greaterdetail.

Referring now to the drawing. with particular reference to FIGS. 14. acamera A is provided which includes a casing 11 having an adjustableobjective lens 12. The lens 12 is adjusted to produce an image of acontinuous event upon the front surface of a lens array or mosaic 13.The lens mosaic 13 is a rectilinear array of a multitude of smallspheres or beads 14 of transparent material such as. for example. glass.These spheres are supported in a substantially fiat plane by means of anopaque binder 15 such as, for example, epoxy interposed in the spacesbetween the spheres 14. The front semi-spherical lens surface 16 and thevery back of each of the spheres 14 is left free of binder material sothat light striking the front surface 16 of each sphere is focused bythe sphere onto a tiny spot at the back of the sphere.

An image mask 17 is positioned behind the lens mosaic 13 and is providedwith a minute aperture 18 at the focal spot for each of the spheres 14.Light incident on the front surface 16 of each sphere is focused throughthe aperture 18 therebehind and diverges from the back surface of themask 17. A film strip or plate 19, moving from a supply reel 21 to atakeup reel 22 by means of a slowly moving drive motor 23 is driven pastthe back of the image mask 17 at a slight angle with respect to the edgeof the rectilinear array of spheres 14 such that light passing througheach of the apertures 18 and focused in a spot on the film plate 19traces an individual streak 24 on the film plate 19. The angle withwhich the film plate is driven with respect to the edge of therectilinear array is selected such that the streaks from all of theapertures are parallel and do not overlap when the film plate 19 is runthe length of the lens mosaic 13. The streak produced by each sphere 14varies in intensity in accordance with the intensity of the portion ofthe image that is produced on the front surface 16 of that sphere torecord the variation in that particular portion of the image of theevent being photographed. The film is developed and processed in theconventional manner.

A pressure plate 25 holds the film plate 19 securely in place in aprecisely aligned film track. The film plate 19 is slightly wider thanthe lens mosaic and the length of the film plate is determined by thelength of the lens mosaic, the resolving power of the film and theperiod of time for which it is desired to record.

The streaks 24 produced by these lenses are illustrated in FIGS. 3 and4. As illustrated, between two spheres in any row running transverselyof the film are positioned the streaks for a sphere in every row in thelength of the lens mosaic 13. In order to maintain a distinct streak foreach sphere in the rectilinear array illustrated in FIG. 3 the diameterof each aperture 18 in the mask 17 must be less than the diameter of thespheres divided by the number of spheres in a line aligned substantiallyparallel to the direction of film motion. The resolving power of thelens mosaic 13 and thus the definition of the recorded image on the filmplate 19 is a function of the number and size of lens elements, providedthat each sphere transmits light through its corresponding image maskaperture.

The size of the lens mosaic is illustrated in phantom in FIG. 4 asincluding that portion of the film in which all the streaks originate,the number of streaks illustrated being only a sufficient number toillustrate the invention. As is clear from the example given below thenumber of streaks typically is in the thousands and may be in the orderof hundreds of thousands.

Since the effect of the lens mosaic 13 is to greatly reduce the recordedimage element size, the film may be traversed at a rate very much slowerthan is possible with conventional motion picture cameras. For example,an hour of action which is to be viewed on a 17" screen might berecorded on a film plate whose dimensions are 17 inches wide and 24inches high.

While the film plate has been illustrated as wound on reels 21 and 22.it can be of a rigid flat construction which can be continuously drivenat a precise speed by any one of a number of drive means such as, forexample, a worm ear.

Instead of the perfectly rectilinear array of spheres 14 as shown inFIG. 3, staggered rows of spheres such as illustrated in FIG. can beutilized as well as a circular array of spheres provided that care istaken to prevent overlapping of the streaks on the film plate. However,according to the arrangement of FIG. 5, the length of the picture thatcan be taken is less since the streaks traced by two heads arrangedtransversely of the film are closer together and a smaller number ofbeads must be provided longitudinal of the mosaic. Also, since inreproducing the image a lens mosaic which is substantially identical tothe camera lens mosaic must be used, a precise yet easily reproduciblemosaic structure must be employed.

According to the presently described embodiment of this invention thenecessity for a continuously operating shutter is avoided although asingle action shutter, opening at the beginning of the photographedevent and closing at the end of the event, is used to advantage.

Instead of a separate mask 18 the opaque binder may be utilized for themask, provided however that the size of the exposed portions of thespheres 14 on the back side of the mosaic is accurately controlled.

The image mask illustrated in the drawing may be produced by coating thesurface of the lens mosaic with an emulsion and applying a photographicfilm plate against the lens surface to develop the film plate in theminute points of contact with the emulsion. Then a positive is producedwhich has transparent portions only at the places of contact between thefilm and mosaic. This will provide a mask with a transparent apertureappropriately positioned behind each lens.

Alternatively, the mask may be made by directing parallel light throughthe lens mosaic so that light from each lens is focused upon a very highcontract emulsion, which, when developed, produces transparent portionsin the film plate to serve as mask apertures.

Instead of the construction described above the lens mosaic may bemolded entirely of a single material such as shown in FIG. 6. To producesuch a mosaic a plurality of substantially perfect spheres such asappropriately sized ball bearings are arranged in the desired closelypacked array. A mold material such as silicone rubber is then pouredover the array and cured. Then, after the spheres have been removed themold material is filled level with a lens material such as, for example,plastic which, upon hardening, is transparent. Once the lens materialhas hardened and has been removed from the mold material the lens mosaicis complete.

Referring now to FIGS. 7-10, there is shown a pro jection apparatus B inwhich light from a parallel light source generally indicated at C isdirected through a lens mosaic, an image mask and a developed exposedphotopositive film plate onto a screen D.

The source of parallel light C includes a wedge 31 of transparentmaterial such as. for example, plastic having a narrow end and a wideend. The wedge 31 includes first and second substantially fiat planefaces 32 and 33 arranged at a slight angle with respect to one another.Light is directed into the transparent wedge 31 from a bulb 34 which ispositioned within a transparent head 35 positioned at the wide end ofthe wedge 31 and of heat resistant and heat absorbent material such as,for example, glass. Glass is used for the head 35 so as to physicallyremove the light source 34 from wedge 31 whereby the wedge may be ofnon-heat resistant material if desired. The outside exposed faces of thetransparent head 35 and of the wedge 31. except face 33, may be coatedwith a layer 36 of reflecting material such as, for example. silver toproduce light reflections within the head 35 and wedge 31.

Positioned against the wedge face 33 is a directing plate or lightpickup lens 37 of transparent material, preferably the same material asthe wedge 31. The lens surface adjacent the wedge 31 is provided with agrooved surface. saw-toothed in cross-section. with each of the groovesaligned parallel with the line of intersection of the planes of wedgefaces 32 and 33, while the opposite surface of the lens is a planesurface substantially parallel to the wedge face 33. One side 38 of eachof these teeth or grooves is aligned substantially perpendicular to thewedge face 33 while the other side 39 is positioned at an angle ofsubstantially 45 with respect to the face 33 and inclined with respectto the face 33 in the same direction as the face 32. The inclined side39 is covered with a layer of reflective material such as silver toproduce internal reflections in the lens 37.

Light directed into the wide end of the wedge 31 is reflected back andforth from the faces 32 and 33, the angles of inclination increasingwith each reflection due to the slight angle between the faces 32 and33. When the angle of inclination just exceeds the critical angle of thewedge material, the light passes out of the face 33 traveling almostparallel therewith. This light then enters the saw-tooth surface of thepick-up lens 37 by passing substantially perpendicularly through thetooth sides 38 and, after internal reflection from the mirrored inclinedside 39, emerges from the opposite plane surface of the pick-up lens 37substantially perpendicular thereto. In practice the inclined sides 39of the lens teeth are inclined at an angle just slightly greater than 45to properly reflect light traveling almost parallel with the wedge face33. The bulb 34, the wedge 31 and pick-up lens 37 jointly provide evenlydistributed, substantially parallel light onto the front surface of amosaic lens 41 substantially identical to the mosaic lens 13 used toexpose the film plate 19 in the camera illustrated in FIGS. 1-4.

As illustrated clearly in FIG. 10, this parallel light is focused by themosaic lens 41 through apertures 42 in an image mask 43 positionedagainst the fiat side of the mosaic lens 41. The light passing throughapertures 42 falls on the exposed streaks of a developed film plate 44which was exposed by the camera A. The varying opaqueness of the streakson this exposed film 44 permits light of varying intensities to passthrough the film 44 onto the screen D. As the exposed film plate 44 isadvanced by a drive wheel 45. a continuous image of the photographedevent is reproduced on the screen D.

Horizontal registration of the film plate 44 and the mask 43 must beprecise so that each streak on the film plate is precisely under theappropirate lens corresponding to a lens which originally generated thatstreak, and vertical registration is also critical so that the event isreproduced from its beginning.

The screen D, preferably of the same material as the lens mosaic 41, hasone surface which bears against the film plate 44 to hold the plateagainst the mask 43 and has an opposite frosted surface on which thereproduced image appears. This screen has an effective thicknesssubstantially equal to the thickness of the mosaic lens 41 so that eachspot of light is magnified to the same extent that the image on themosaic lens surfaces was reduced in producing the film plate streaks. Bypermitting the light to diverge from the film plate for the samedistance over which it was initially converged each fragment of therecorded image is properly magnified so that the fragments fuse into aperfectly reconstituted halftone picture. If the screen is of a materialdifferent from that of the lens mosaic, the screen thickness must besuch that it is the same effective thickness as the lens mosaic.

Alternatively, the screen may be a lens mosaic identical to the mosaic41 but reversed in direction to redirectionalize the light passingthrough the film 44 to produce an image on the lens surface of thisadditional lens mosaic substantially identical to the image produced onthe film plate by a similar lens mosaic in the camera A.

Also, the film plate and the screen can be combined in a laminatedelement having a thin film lamination containing the streaks provided onone side of the element and a frosted screen provided on the other sideof the element, the element having the same effective thickness as thelens mosaic.

The viewing apparatus in FIGS. 7, 8 and 9 is provided with a sound trackto accompany the visual display of the recorded image. The sound trackis recorded on the film plate 44 by light streaks running the length ofthe film plate similar to those producing the visual information. Thesound track play back structure includes a continuous narrow belt 51such as, for example, steel supported between an idler wheel 52 and adrive wheel 53 located respectively above and below the parallel lightsource C along the edge of the film plate 44. The surface of the pick-uplens 37 adjacent the lens surface of the lens mosaic 41 is provided witha notch 54 which permits this tape to run the length of the film plate44. The belt 51 is provided with three equally spaced apart horizontalslots 55 so positioned that one slot is always in the sound track at anygiven time. The drive wheel 53 is driven by a variable speed motor 56. Astrip photocell 57 runs the length of the film plate 44 on the oppositeside thereof from the belt 51 in order to detect the light signals whichproduce the sound track. The belt 51 is run at such a speed with respectto the film plate 44 that light transmitted through the horizontal slots55 from the pick-up lens 37 scans downwardly across the film plate 44.The light passing through the film plate 44 is of varying intensity dueto the sound track on the film plate and is detected by the stripphotocell 57. The output of the photocell is sequentially applied to avoltage amplifier 60, an equalizer 61. a power amplifier 62 and a loudspeaker 63 to produce sound.

The speed of optically scanning this sound information on the film plateis the same as the initial speed with which the sound information wasrecorded on the film plate but does not exceed the speed of one fullsweep per frame equivalent movement of the film plate. The speed isoptically synchronized by synchronizing the maximization of a timingmarker (not shown) on the edge of the film plate with the mediumposition of a slot over a separate pick-up lens segment 64 below thepick-up lens 37 utilizing a photocell pick-up 65 for operating a servomechanism 66 to correct the speed of the motor 56. The back surface 67of the lens segment 64 is provided with an optical surface graded fromtransparent at one end to opaque at the other.

Optional sound track systems are illustrated in FIGS. ll-14.

Referring now to FIGS. 11 and 12, the sound track is produced byhorizontally scanning separate horizontal lines on the film plate as thefilm plate is moved longitudinally through the viewing apparatus. Morespecifically, a horizontal slit 71 is provided in the image mask 72along one edge of the film plate for illuminating a narrow horizontalportion of the film plate which is provided with sound track informationrecorded on horizontal lines 73. This horizontal slit is scanned by ahorizontally directed flying spot which is created by shining lightthrough a transparent, internally light reflecting cylindrical rod 74which is provided with a spiral 75 scratched in the surface thereof topermit passage of light therethrough along the spiral. When the rod 74is rotated and end illuminated, the horizontal slit 71 is scannedhorizontally by a light spot created by the spiral 75 on the rod 74. Thelight passed through the film plate with this arrangement is picked upand converted into a sound track in the same manner as illustrated inFIG. 9.

Still a further alternative sound track system is illustrated in FIGS.13 and 14 wherein a light band chopped at different frequenciescorresponding to an audio frequency spectrum illuminates a narrowhorizontal slit in the image mask and certain portions of this spectrumare passed through the film plate by the sound track information 81recorded on the margin of the film plate 80. This information is pickedup by a photocell detector and amplified in conventional fashion toproduce the sound accompanying the visual image. The frequency spectrumcan be produced in a manner illustrated in FIG. 14 by a rotatingcylinder 82 on the surface of which are provided bands 83 of alternatelytransparent and blocked out areas to produce light chopped at differentfrequencies. Light directed on the back of the cylinder 82 is focused toa narrow line in alignment with the narrow slit in the image mask forpassing the spectrum of chopped light through the margin of thet filmplate. Sound track information 81 recorded on the film plate permitspassage of the desired chopped light frequencies which are thenconverted to sound in the conventional manner. The chopping frequency isthe product of the rate of rotation of the cylinder and the number oflight and dark segments around its circumference. This number of lightand dark segments is varied lengthwise of the cylinder to constitute aspectrum of audio frequencies when it is rotated. All of the frequenciestransmitted through the narrow slit and sequentially differentiallytransmitted through the sound track on the film plate are collectedadditionally by a photocell, amplified and rendered as audio sound.

By way of example, a typical viewing apparatus is illustrated in FIGS.15-17 along with the film plate that is inserted therein. The viewerconsists of a casing 91 provided therein with a parallel light source, alens mosaic and an image mask of the type described above. The casing isprovided with a viewing window 92 and a slot 93 to receive a film plate94 whereby the picture can be viewed through the viewing window 92. Thefilm plate is inserted in the viewing apparatus and a cocking lever 95depressed to position the film plate ready for producing a pictorialimage of a continuous event previously photographed and recorded in theform of vertical streaks 90 on the back of the film plate 94. The frontof the film plate is provided with a frosted surface 96 which serves asthe screeen for the viewing apparatus. A sound track is reproduced witha speaker 97 which is provided in the casing 91.

In a typical embodiment of the present invention a toy viewing apparatusproviding reasonably good resolution is provided with a lens mosaic 3inches high and inches wide that covers the entire film plate includingsound track, a viewing screen 3 inches high and 4 inches wide and an 8"x 5" film plate. The lens mosaic is made up of 25 lenses to the linearinch or a total of 9,375 lenses, each of the lenses having a diameter of.04", the apertures in the image mask behind the lens mosaic having adiameter of about .00053". By moving the film plate at a speedequivalent to 16 frames per second, a film plate approximately 8"longwill produce a continuous visual image over a 10 minute running time.

As an alternative embodiment, the present invention is utilized for amicrofilm card reader by providing a shutter in the camera so that witha time exposure each frame, which consists of one recorded spot for eachof the lenses in the lens mosaic, provides a single frame on the filmplate. Thus, each frame can constitute a picture of a printed page, andthus a book several hundred pages in length can be recorded forreproduction on a small film card. In the viewing apparatus for such afilm card reader, the film plate is advanced manually or in measuredincrements for reproducing successive photographed pages.

Instead of recording the light spot images from all of the lenses of alens mosaic in streaks lengthwise of a film plate, the film plate mightbe moved with respect to the lens mosaic to trace a streak which istraced parallel to every other streak but with each streak tracing aspiral or a raster such as shown in FIGS. 18 and 19 respectively. Suchan arrangement would be particularly well adapted for use in a microcard reader and the number of possible frames would be approximately thearea behind each of the lenses divided by the area of one of theapertures in the image mask.

In all embodiments of the invention the optical elements of the cameraand viewing apparatus are made of the same material so as to avoiddifferential expansion and problems caused by different indecises ofrefraction.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity ofunderstanding, it is understood that certain changes and modificationsmay be practiced within the spirit ofthe invention as limited only bythe scope of the appended claims.

I claim:

Apparatus for producing parallel light comprising in combination: asolid wedge of transparent material having a thick end and a thin endand having two substantially flat plane faces extending between saidends and inclined at a slight angle with respect to one another, meansfor directing light into said wedge at said thick end thereof, and atransparent light directing plate having one surface positioned againstone of said fiat faces of said wedge, said one surface of said directingplate provided with a plurality of substantially identical groovesaligned substantially parallel to the line of intersection between theplanes of said wedge faces, one side of said grooves being substantiallyperpendicular to said one fiat face of said wedge and the other side ofsaid grooves inclined at an angle of substantially to said one wedgeface with said grooves tapering inwardly in said light directing plateand in a direction toward said thin end of said wedge.

No references cited.

JEWELL H. PEDERSEN, Primary Examiner.

R. J. STERN, Assistant Examiner.

